Rotary drill assembly

ABSTRACT

A rotary drill bit assembly is disclosed comprising a cylindrical body having a central opening in the lower face thereof which defines a chamber therewithin. An annular main cutting head is carried at the lower end of the body, and a supplemental bit assembly is supported from within the chamber which has an annular cutting head disposed perpendicular to the axis of the body and eccentric thereto. The outer radius of the supplemental cutting head and inner radius of the main cutting head substantially coincide along a line parallel to the body axis, with the outer radius of the supplemental head also extending at least to the axis of the central opening. Means are provided for rotating the supplemental cutting head relative to the main cutting head.

i atut 1 n1 1 mte States [is] muss Stuart Feb. 11972 [54] ROTARY DRILLASSELY 3,161,243 12/1964 Davis ..l75/3l9 X [72] Inventor: 111321;]:13739 Hughes Lane, Pfimary Emminer Mawin A. Champion I AssistantExaminer-Richard E. Favreau [22] Filed: Dec. 12, 1969 Attorney-Raul,Glaser& Harwood [21] Appl. No.: 884,494 [57] ABSTRACT A rotary drill bitassembly is disclosed comprising a cylindrical [22] its}? ..175/107,l75/33Iil2ll7lfgg; body having a central opening in the lower facethereof which d 376 173 defines a chamber therewithin. An annular maincutting head 1 e o 175/202 9 is carried at the lower end of the body,and a supplemental bit assembly is supported from within the chamberwhich has an annular cutting head disposed perpendicular to the axis ofthe [56] Rem-em cued body and eccentric thereto. The outer radius of thesupple- UNITED STATES PATENTS mental cutting and inner radius of themain cutting head substantially coincide along a line parallel to thebody axis, 2,030,015 2/ 1936 Y---- 175/3 x with the outer radius of thesupplemental head also extending 2,619,325 11/1952 175/107 at least tothe axis of the central opening. Means are provided 2,626,780 1/1 953011105 175/107 for rotating the supplemental cutting head relative tothe main 2,709,574 5/1955 Arutunoff ..175/ 101 cutting head 2,877,9883/1959 Cameron et al. ....l75/319 3,077,936 2/1963 Arutunoff ..l75/404 X8 Claims, 8 Drawmg' Figures 5o 54 so k M 62 M 64 52 ii 5| M f a 1 so 80L I 44 a 2 361K 43 1 r 47 42 3/ I7 l 43 34 "l 34 s 4 7 K 36\ 7 g 22 1 36It 3? 7 45 a: L?

33 41 3 Q 30 I g 47 Q v I 3| I 25 L 3| I 8 B8 i I zl/ l0 7 23' \YPATENIEB FEB 81972 3,640,352

sum 2 or 4 FIG. IB

lNVE/VTOI? ROBERT W. STUART AMZ, HASH l IVA/WW0 A TTORNEYS i mzmin m8:972 I 3,640,352

8HEET3UF4 I2 22 t 84 23 [M 88 FIC3.2

FIG.3

MIII/ENTOR ROBERT w. STUART ATTORNEYS PATENIED FEB 8 m2 3.640.352

saw u or 4 l/VVE/VTOR ROBERT W. STUART M17], HASH & l/MWW ROTARY DRILLASSEMBLY This invention relates to rotary drill bit assemblies, and moreparticularly to a rotary drill bit assembly having an annular maincutting head and a supplemental cutting head disposed within the maincutting head for disintegrating material within the inner radius of themain cutting head.

Many improvements have been made in diamond drill bits in the pastseveral years, with the aim of achieving better performance, less wear,faster drilling operations and many other features. One type of diamonddrill bit employed comprises a cylindrical body adapted to be secured atits upper end to a drill collar and which carries an annular maincutting head at the lower end thereof. The cylindrical body has acentral opening in the bottom thereof which defines a chamber within thebody for receiving a core therein left by the main cutting head. Thecentral core is left as the annular main cutting head penetrates thematerial being drilled. These bits also have supplemental bits supportedfrom within the chamber that disintegrate the central core as the entireassembly penetrates the material.

Although this type of bit has many advantages, several problems areencountered in the use of these drill assemblies as they now exist. Forexample, all of these bits are supplied with drilling fluid underpressure to cool the cutting faces and to wash the cuttings up the sidesof the drill stem. However, the available assemblies are not designed toachieve maximum advantage and use of the drilling fluid. Efficientcutting of the core within the confines of the main drilling face alsobecomes a problem if the core crumbles into relatively large pieces.Several other problems are encountered and will be discussed in moredetail below. However, it is this type of drill bit assembly to whichthe present invention is directed.

To achieve a better understanding of the invention as will be describedin detail hereinafter, several objects should be kept in mind. It is oneobject of the invention to provide a rotary drill bit assembly of thetype generally described above that has the feature of improved drillingfluid distribution over the faces of both the main cutting head and thesupplemental cutting head. This feature of the invention provides muchbetter cooling of the cutting faces during drilling, and washes away thecuttings more efficiently. Another object is to provide means Within theassembly to apply the fluid under pressure directly to the surface beingdrilled, thereby achieving much better control in flushing awaycuttings. Yet another object is to maximize the efficiency with whichthe supplemental bit cutting face can cut away the core left by the maincutting face, while at the same time eliminating the jamming of thesupplemental bit that ordinarily results from core crumble. Stillanother object is to require a minimum amount of torque to rotate thesupplemental cutting head for any given penetration rate, and to requirea minimum increase in torque required to rotate the supplemental cuttinghead as the penetration rate is increased such as by adding weight, forexample.

Briefly, the drill bit assembly of the invention comprises a cylindricalbody adapted to be secured at its upper end to a drill collar, and whichhas a central opening in the lower face thereof defining a chamberwithin the body. An annular main cutting head is carried on the lowerend of the body through which the chamber opens. A supplemental bitassembly is supported from within the chamber which has an annularcutting head disposed perpendicular to the axis of the body andeccentric thereto. The outer radius of the supplemental cutting head andinner radius of the main cutting head substantially coincide along aline parallel to the axis of the body with the outer radius of thesupplemental head also extending at least to the axis of the centralopening of the body. Means are provided within the body for rotating thesupplemental bit rela tive to the cylindrical body, or relative to themain cutting head. The supplemental bit is also rotated with the maincutting head. In one embodiment, the annular cutting head of thesupplemental bit is disposed above the face of the main cutting head,thereby effecting the cutting away of the core left by the main cuttingbody extending up into the central opening. In yet another embodiment,the annular cutting face of the supplemental bit extends below the faceof the main cutting body, thereby cutting a cylindrical hole in advanceof the main cutting body.

Any suitable means can be employed to rotate the supplemental bitrelative to the main cutting body, such as fluid actuated motorcomprising vanes attached to the supplemental bit and to the interior ofthe cylindrical body. An electric motor, for example, can also beemployed for this purpose. In the case of a fluid motor, drilling fluidis passed between the vanes to cause relative rotation between thecylindrical body and the supplemental bit. Passages are provided in theassembly to transmit the drilling fluid to the cutting faces. 4

An important feature of the invention is in the provision of the annularcutting head of the supplemental bit perpendicular to the axis of thebody, so that the face thereof is horizontally disposed during thevertical drilling operations. The annular configuration of thesupplemental head provides more efficient cutting and removes all of thematerial between the annular main cutting head as it is rotated.

Other objects, features and advantages of the invention will becomereadily apparent from the following detailed description thereof whentaken in conjunction with the appended claims and the attached drawingwherein like reference numerals refer to like parts throughout theseveral figures, and in which:

FIG. 1A is a fragmentary, side elevational view, in section, of thelower portion of one embodiment of the rotary drill bit assembly of theinvention;

FIG. 1B is a fragmentary, side elevational view, in section, of theupper portion of the embodiment shown in FIG. 1A;

FIG. 2 is a bottom view of the drill bit assembly shown in FIG. 1A;

FIG. 3 is a section view of the assembly shown in FIG. 1A, taken throughsection lines 3-3 thereof;

FIG. 4 is a fragmentary, side elevational view, in section, of thebottom portion of another embodiment of the invention;

FIG. 5 is a fragmentary, side elevational view, in section, of thebottom portion of a drill bit assembly according to another embodimentof the invention;

FIG. 6 is a bottom view of the assembly shown in FIG. 5; and

FIG. 7 is a fragmentary, side elevational view, in section, of thebottom portion of a drill bit assembly according to yet anotherembodiment of the invention.

One embodiment of the invention is shown in FIG. 1A, with FIG. 1Bshowing the upper portion thereof. Reference is also made to the bottomview of this assembly shown in FIG. 2, and the sectional view of thefluid motor shown in FIG. 3. This assembly comprises an annular, maincutting head 10, with diamonds held in the bottom and outer surfacesthereof forming a cutting face 12, to cut away the material 14therebeneath. The main cutting head has a central recess 11 therein intowhich extends a central core 16 of the material left by the main cuttinghead. The main cutting head is secured by any suitable means to acylindrical body 18, and the cylindrical body is attached at its upperend to a cap 72 as shown in FIG. 18. It will be understood that the capis attached to the lower end of a drill stem. The cylindrical bodydefines a chamber 81 therein for accommodating a supplemental bitassembly to be described hereinafter, and through which drilling fluidis forced to emerge at the cutting faces. The outside diameter of themain drilling head is larger than the outside diameter of thecylindrical member 18 and drill stem, so that an annular space 19 isleft between the cylindrical body and the sidewall 17 of the hole as thedrill progresses downward. Thus cuttings can pass up the base holethrough space 19.

A supplemental bit assembly 20 is supported from within the chamber 81of the cylindrical body 18, and terminates in an annular lower bit end21 having an annular, diamond cutting face 22. The annular face 22 isdisposed above the lower extremity of the face of the main cutting headto cut away the core 16 that extends upward into chamber 11, and iseccentric relative to the axis of the cylindrical body. The periphery ofthe supplemental head also substantially coincides with the inner radiusof the main cutting head along a line parallel to the axis of theassembly, and extends at least to the axis of the opening 11 within themain cutting head, all as shown. As will be seen hereinafter, means areprovided for rotating the supplemental bit relative to the main cuttinghead, while at the same time, the supplemental bit and face thereof arecarried with the main drilling head as the latter is rotated. Thus anannular cavity is drilled by the main cutting head, whereas the annularface of the supplemental bit cuts away the core as the supplemental bitis rotated with the main head while also being rotated relative thereto.[t is important to note that the face of the auxiliary head isperpendicular to the axis of the cylindrical body, so that all of thebottom surface thereof is in contact with the material 16. This alsocauses the face of the supplemental head to be horizontally disposed ifthe entire assembly is vertical. In addition, the cutting face of thesupplemental head extends between the edge of the core and at least thecentral axis of opening 11, so that all of the core is removed. Betterfluid distribution is provided across this face because of the fullcontact between the cutting face of the supplemental head and the core.In contrast, much poorer fluid distribution is achieved when the cuttingface of the supplemental head overhangs the core, for example, or whenthis face is disposed at an angle to the top surface of the core. Aminimum amount of torque is required to rotate the supplemental annularhead, whereas a much greater torque is required if the head has a fullcircular face. In addition, less effective cutting is achieved for afull face.

The lower portion or head 21 of the supplemental assembly extendsupwardly in the chamber and constitutes a lower extension of acylindrical main body portion 24. The head portion 21 may be threadedonto the main body, along threads 26, for example. The head 21 defines achamber 23 therein that communicates with a chamber 25 defined withinthe main body portion 24 through opening 28 in the bottom of the mainbody portion. The main body portion 24 also includes a solid stem 50constituting an upward extension thereof, which stem extends upward intoa cap 72 as will be described.

Although various bearing arrangements can be employed to support thesupplemental bit assembly within the body 18, a description of onespecific arrangement will now be given. A generally annular, elongatedlower bearing assembly 30 is seated within the body 18 in the lower endthereof on corresponding beveled shoulders 31 provided on the assemblyand the inner wall of the body. Circumferentially spaced apart rubberribs 32 are vulcanized onto the inner wall of the assembly and extendessentially along the vertical length thereof. Thus vertical passagewaysare provided between adjacent ribs for the passageway therethrough ofdrilling fluid. Rubber is employed as the bearing surface to minimizewear thereof due to cuttings produced by the drilling operation.

Another component of an upper thrust bearing assembly is stacked ontothe top shoulder of the lower radial bearing assembly, and comprises afull bearing assembly 34 having a vulcanized face 35, a firsthalf-assembly 37 having a rubber face 38 adjacent assembly 30, anannular, metal spacer 36 separating assemblies 34 and 37, anotherhalf-assembly 37' having rubber face 38 disposed at the top, and anotherspacer 36 separating assemblies 34 and 37. It will be understood thatthe parts are stacked one on the other in the order shown, with theouter bearing assembly being radially spaced apart from the innercomponent to be described below. Another annular spacer 39, having ports40, is stacked on top of the upper bearing assembly.

An annular shoulder and spacer 41 surrounds the main body 24 of thesupplemental bit and is held between the top of the head portion 21 andshoulder 45 on the main body. A thrust disc 42 is stacked on andsupported by spacer 41, an annular thrust sleeve 43 is stacked on andsupported by disc 42,

and additional disc 42 and sleeve 43' are carried thereabove as shown,with sleeve 43' abutting shoulder 44 of the main body. All of components41, 42, 43, 42 and 43' are assembled onto the main body portion and thensecured in place as the head portion 21 is threaded onto the lowerportion of the main body. A tortuous passageway 47 is provided betweenthe bearing assemblies on the body 18 and the discs and sleeves on thesupplemental bit for the passage therethrough of fluid. Moreover, asmall space 48 is left between the main cutting head 10 and supplementalhead 21 for the passage of fluid therebetween. The supplemental bitassembly seats within the body 18 with the discs 42 and 42' bearing downon bearings 37 and 34, respectively, when the supplemental head is notbearing on core 16. During drilling when the supplemental head bearsagainst the core, however, the supplemental assembly is urged upwardslightly, so that an effective fluid bearing is provided between thebody 18 and bit stem 24.

A plurality of annular members 54 are stacked about the solid upperstern portion 50 and are supported from shoulder 51 thereof. Each ofthese members support a plurality of circumferentially, spaced apartvanes 52 that are angled from the vertical, seen more clearly in FIG. 3.Thus several vertically spaced apart groups of vanes are secured to stemportion 50. Similarly another plurality of annular members 62 arestacked against the inner wall of member 18 and are supported fromspacer 39. Similar vanes 60 are supported from these members (see FIG.3), with an annular support 64 surrounding stem portion 50 for givingadditional support to these vanes. The ends of vanes 52 are spacedslightly from members 62 on the wall of body 18, and the ends of vanes60 (or supporting member 64) are spaced slightly from members 54, sothat no contact is made between the two assemblies. It will be realizedthat vanes 60 are also angled from the vertical but in an oppositemanner than are vanes 52. Thus a fluid motor is provided for rotatingthe supplemental bit assembly as fluid is forced under pressure down andbetween the vanes through passageway 56.

Referring particularly to FIG. 18, a nut 66 is threaded over the top ofstem portion 50 and bears down against the stacked assembly comprisingcomponents 54. The inner vanes are held in place and prevented fromslipping about the stem in this manner. A recess 67 is provided in thetop surface of body 18, so that a pin 68 can be inserted therein thatextends upward out of the recess. A circular plate 69, having an opening71 provided in one side therein and a recess 70 in a lower face of theother side, is positioned on top of members 62 to bear thereon, withrecess 70 receiving the protruding pin 68. Opening 71 is considerablylarger in diameter than nut 66, so that an ample passageway is providedfor fluid to pass from within the cap down onto the fluid motor. The cap72 is threaded down within an upstanding annular top portion 73 of thebody 18 along threads 74, so that the bottom rim of the cap bears downagainst plate 69. This arrangement thus serves to secure vanes 60 inplace to prevent them from slipping on the inner wall of body 18. Thecap is hollow with a chamber 75 therein, and threads 78 are providedabout the upper neck 76 for securing the cap to drill collar. A port 77provides communication between the interior of the drill collar andchamber 75.

The lower end of stem portion 50 is provided with a plurality of ports80 that provide communication between the chamber 81 beneath the vanesand the hollow bore 25 of main body portion 24. Thus a continuouspassageway is provided for the drilling fluid through space 56 betweenthe vanes, chamber 81, ports 80, down through bore 25 and chamber 23 tothe cutting faces. A plurality of bores 84 (only one being shown in FIG.1A) are provided in the cylindrical body 18 ec centric to the axisthereof, with corresponding ports 86 provided for communication betweenthese bores and chamber 81. Bores 84 are circumferentially spaced apartand are provided up through body 18 generally opposite the supplementalbit assembly. These bores are open on the bottom ends 88 thereof, sothat a part of the drilling fluid can also pass therethrough into thevicinity of the main cutting head.

From the foregoing description, it will be seen that the supplementalbit is caused to rotate relative to the main cutting head as drill fluidis forced through the fluid motor, while the supplemental bit is alsocaused to rotate with the main head as the latter is rotated. Thesupplemental cutting head bears flush against material 16 with the planeof the face being disposed horizontally when the axis of the assembly isvertical. The supplemental head tends to cut an annular cavity, butactually disintegrates the core as it is rotated in a circular patternon an eccentric to the axis of the main head. The two heads do notoverlap, but the supplemental head extends to the very edge of the coreto remove it entirely. Thus no part of the core is left that can createand cause jamming. Because of the horizontal, flush fit against thecore, even fluid distribution is achieved over the cutting face.Moreover, even fluid distribution is attained on the main cutting face.

It will be realized that different type motors can be employed to rotatethe supplemental bit assembly, such as an electric motor installedwithin or above the body 18. Moreover, such a motor, or other means, canbe employed to rotate the main cutting head, rather than rotating themain head by rotating the drill stem.

Another embodiment of the invention is shown in FIG. 4, wherein only thelower portion of the entire assembly is changed. In contrast to the faceof the supplemental cutting head being elevated above the face of themain cutting head as in the embodiment just described, the supplementalhead extends below the main head. Thus an annular lower head 100 isprovided with a diamond cutting face 102 provided therein. The head 100therefore cuts a circular cavity 104 in advance of the main head, inwhich the diameter of this cavity is substantially equal to the insidediameter of the main cutting head. Otherwise, the construction andoperation are as previously described. This embodiment has particularapplication for drilling in relatively soft formations, such as sand,for example, whereas the first described embodiment is effective indrilling in hard formations. As to the soft formations, much fasterpenetration can be achieved with the assembly shown in FIG. 4.

Still another embodiment is shown in the fragmentary view of FIG. 5 andthe view thereof in FIG. 6. In contrast to the entire supplementalassembly being disposed eccentric to the main assembly axis, thesupplemental assembly of this embodiment is aligned axially within body18, but is also rotated relative thereto. The supplemental assembly issupported from within the main body by suitable bearing assemblies 112(shown schematically) and comprises a lower end 110 disposed adjacentthe lower end of the main assembly within the inner diameter of mainhead 10. A small annular space 120 is again provided between the mainand supplemental heads for the passage of fluid therethrough. The lowerend 110 carries an annular cutting head 114 on the bottom thereof thatis eccentric to the central axis of the assembly, and which ispositioned relative to the main head as earlier described. Thesupplemental cutting head is again raised with respect to the maincutting head for disintegrating a core that extends up into the mainhead. A fluid channel 116 is provided in the supplemental assembly alongits axis, but which is offset to open through the face of theeccentrically disposed cutting head. Thus the supplemental head iscaused to be rotated in an annular pattern to disintegrate the core,while the entire supplemental assembly is also rotated with the mainhead.

An embodiment similar to that just described is shown in FIG. 7, whereinthe supplemental head 134 carried by the lower end 132 is disposed belowthe main head. The operation and structure is otherwise the same, withthe relative features and applications having already been discussed.

Although the invention has been described with reference to specificembodiments thereof, it will be well understood that many modificationsand substitutions can be made that do not depart from the true scopethereof. Accordingly, it is intended that the invention be limited onlyas defined in the appended claims.

What is claimed is:

l. A rotary drill bit assembly comprising:

a. a cylindrical body having a central opening in the lower face thereofdefining a chamber therein,

b. an annular main cutting head carried by said body at the lower endthereof,

c. a supplemental bit assembly supported from within said chamber andhaving an annular cutting head whose outer diameter is less than theinner diameter of said main cutting head disposed eccentric to the axisof said body and whose face is perpendicular to said axis,

d. the outer extremity of said supplemental cutting head substantiallycoinciding with the inner extremity of said main cutting head along aline parallel to the axis of said body, but in nonoverlappingrelationship therewith, and extending at least to the axis of said maincutting head, and

e. means for rotating said supplemental cutting head relative to saidmain cutting head.

2. A drill bit assembly as set forth in claim 1 wherein the face of saidsupplemental cutting head is above the face of said main cutting head.

3. A drill bit assembly as set forth in claim 1 wherein the face of saidsupplemental cutting head extends below the face of said main cuttinghead.

4. A drill bit assembly as set forth in claim 1 wherein said means forrotating said supplemental cutting head relative to said main cuttinghead comprises a fluid motor.

5. A drill bit assembly as set forth in claim 1 wherein said bodyincludes a first passageway opening adjacent said main cutting head forthe flow of fluid therethrough, and said supplemental bit assemblyincludes a second passageway opening within the face of saidsupplemental cutting head for the flow of fluid therethrough.

6. A drill bit assembly as set forth in claim 1 wherein said maincutting head has an interior cylindrical surface, and said supplementalcutting head has an exterior cylindrical surface that is substantiallycontiguous to said interior surface along said line parallel to the axisof said body.

7. A drill bit assembly as set forth in claim 1 wherein saidsupplemental bit assembly includes a generally cylindrical stemsupported within said chamber eccentric to the axis thereof, and saidsupplemental cutting head is carried by said stem at the lower endthereof, whereby said stem and said supplemental cutting head arerotated with said cylindrical body eccentric to said axis.

8. A drill bit assembly as set forth in claim 1 wherein saidsupplemental bit assembly includes a stem supported within said chamberconcentric with the axis thereof, and said supplemental cutting head iscarried by said stem at the lower end thereof in eccentric relation tothe axis of said body, whereby said stem and said supplemental cuttinghead are rotated with said cylindrical body.

1. A rotary drill bit assembly comprising: a. a cylindrical body havinga central opening in the lower face thereof defining a chamber therein,b. an annular main cutting head carried by said body at the lower endthereof, c. a supplemental bit assembly supported from within saidchamber and having an annular cutting head whose outer diameter is lessthan the inner diameter of said main cutting head disposed eccentric tothe axis of said body and whose face is perpendicular to said axis, d.the outer extremity of said supplemental cutting head substantiallycoinciding with the inner extremity of said main cutting head along aline parallel to the axis of said body, but in nonoverlappingrelationship therewith, and extending at least to the axis of said maincutting head, and e. means for rotating said supplemental cutting headrelative to said main cutting head.
 2. A drill bit assembly as set forthin claim 1 wherein the face of said supplemental cutting head is abovethe face of said main cutting head.
 3. A drill bit assembly as set forthin claim 1 wherein the face of said supplemental cutting head extEndsbelow the face of said main cutting head.
 4. A drill bit assembly as setforth in claim 1 wherein said means for rotating said supplementalcutting head relative to said main cutting head comprises a fluid motor.5. A drill bit assembly as set forth in claim 1 wherein said bodyincludes a first passageway opening adjacent said main cutting head forthe flow of fluid therethrough, and said supplemental bit assemblyincludes a second passageway opening within the face of saidsupplemental cutting head for the flow of fluid therethrough.
 6. A drillbit assembly as set forth in claim 1 wherein said main cutting head hasan interior cylindrical surface, and said supplemental cutting head hasan exterior cylindrical surface that is substantially contiguous to saidinterior surface along said line parallel to the axis of said body.
 7. Adrill bit assembly as set forth in claim 1 wherein said supplemental bitassembly includes a generally cylindrical stem supported within saidchamber eccentric to the axis thereof, and said supplemental cuttinghead is carried by said stem at the lower end thereof, whereby said stemand said supplemental cutting head are rotated with said cylindricalbody eccentric to said axis.
 8. A drill bit assembly as set forth inclaim 1 wherein said supplemental bit assembly includes a stem supportedwithin said chamber concentric with the axis thereof, and saidsupplemental cutting head is carried by said stem at the lower endthereof in eccentric relation to the axis of said body, whereby saidstem and said supplemental cutting head are rotated with saidcylindrical body.